/Engine/Source/Editor/UnrealEd/Public/MouseDeltaTracker.h
Begin tracking at the specified location for the specified viewport.
void StartTracking ( [FEditorViewportClient](API\Editor\UnrealEd\FEditorViewportClient) * InViewportClient, const int32 InX, const int32 InY, const [FInputEventState](API\Editor\UnrealEd\FInputEventState) & InInputState, bool bNudge, bool bResetDragToolState )